As a retired Chef I have used that tip for years, but the best use for it is those lovely small new potatoes. Save having to scrape them just cook them in ordinary water until cooked strain and pop into a bowl of cold water. When they are cool enough to handle, skin them and pop them back into a pan with butter, salt, ground black pepper and fresh chopped mint, ooh delicious.
The other really useful tip, especially when there is just one or two of you, do a painful of potatoes at a time, strain and put into a bowl of cold water, run the tap slowly till they are completely cold, dry and pop into the fridge and use as needed, they are delicious sliced and cooked in your mornings breakfast bacon fat, ummmm